High cholesterol: how to read your September blood test and when it needs treating

The report lands on your phone on an ordinary Tuesday and the first thing everyone does is hunt for the asterisks. Total cholesterol: 232, with an arrow pointing up beside it. From there the reactions split between two extremes: the person who assumes tablets start tomorrow, and the person who remembers that their father had exactly the same numbers and made it to ninety.

High cholesterol is one of the most repeated findings in September blood tests, when people come back from holiday and catch up on the check-ups they had put off. It is also one of the most misread. A single number tells you almost nothing, and the same LDL can be irrelevant in one person and a reason to treat in another.

Which numbers count as high cholesterol

The reference figures for adults aged 20 and over are set out, among other places, in the MedlinePlus page on cholesterol levels, from the United States National Library of Medicine. A total cholesterol below 200 mg/dL is considered desirable, along with an LDL below 100, a non-HDL cholesterol below 130 and triglycerides below 150. HDL runs the other way: above 60 is best, and it counts as low below 40 in men and below 50 in women.

LDL, HDL, non-HDL and triglycerides: what each one measures

Cholesterol does not travel through the blood on its own; it moves inside particles that carry it, and each parameter is named after those particles. LDL carries cholesterol out to the tissues and, when there is too much of it, ends up depositing in the artery wall. HDL makes the return journey to the liver. Non-HDL cholesterol is worked out by subtracting HDL from the total, and has the advantage of capturing every harmful particle at once rather than LDL alone. Triglycerides are a different family of fats, highly sensitive to food, alcohol and sugar.

Why being «within range» is not always being fine

Laboratory reference ranges describe the general population, not your case. A 35-year-old with no risk factors can be perfectly well with an LDL of 115. The same figure in someone who has already had a heart attack is a serious problem that calls for treatment. Comparing blood tests with your brother-in-law makes little sense: the number is always read alongside the rest of the story.

Why high cholesterol causes no symptoms

This is the part people find hardest to accept. High cholesterol does not hurt, does not tire you out, does not cause headaches or heavy legs. It can sit there raised for twenty years without warning while plaque builds up in the artery wall, and the first symptom can be angina or a heart attack outright. As the NHS page on high cholesterol puts it plainly, the only way to find out is a blood test. That is exactly why it is measured routinely in people who feel perfectly well.

There is one exception: strongly inherited forms sometimes leave visible signs. Soft yellowish deposits on the eyelids, nodules on the tendons (particularly the Achilles) or a whitish ring around the iris in someone under 45 are findings that call for a lipid profile straight away. On how this process eventually reaches the heart, we go into detail in our article on coronary artery disease.

The September blood test: what to look at after summer

September concentrates blood tests for a prosaic reason: people come back, pick up their routines and deal with the errands they left in a drawer in June. It is also a good moment because the body is coming off two unrepresentative months of eating out, more alcohol and irregular hours, and that shows up above all in triglycerides and glucose.

At Clínica Eupnea, blood tests are carried out on site, with a morning sample and results discussed in consultation. The basic lipid profile covers total cholesterol, LDL, HDL and triglycerides, and usually comes with glucose, liver function, kidney function and TSH, which is what allows a cholesterol problem of its own to be told apart from one that is a consequence of something else. For an overview of what each block of a blood test contributes, we covered it in our article on the importance of blood tests.

How often the cholesterol test should be repeated

For healthy adults the general guide is every five years between 20 and 40, every one to two years for men aged 45 to 65 and women aged 55 to 65, and yearly from 65. In children, a first measurement is recommended between the ages of 9 and 11. These figures are a starting point: with diabetes, high blood pressure, smoking or a family history of early heart attack, the interval is set by the doctor.

How to prepare for the test

Fasting: what we will ask you and why

The usual instruction is to come fasting for 8 to 12 hours, drinking only water. Total cholesterol and LDL barely move with the last meal; what does change substantially is triglycerides and glucose. Since the lipid profile is almost always ordered together with blood glucose, and since laboratory reference ranges are built around fasting samples, the practical advice stays the same: follow the instruction you are given when you book.

What skews the result without you noticing

Some situations change the lipid profile and are worth mentioning before the sample is taken, because ignoring them leads to the wrong conclusions:

• A recent infection or acute illness, or surgery in the past few weeks, temporarily lowers cholesterol.
• Pregnancy raises lipids physiologically; the real profile is assessed months after delivery.
• A night of heavy dinner or alcohol sends triglycerides up and can distort the calculated LDL.
• A week of impeccable eating right before the test flatters the result and does not reflect how you eat the rest of the year.
• Some medicines (corticosteroids, high-dose diuretics, certain antiretrovirals or hormone treatments) alter lipids.

Your LDL target depends on risk, not on the table

This is probably the point that most changes how a blood test should be read. European cardiology guidelines do not set a single LDL target for everyone; they grade it by each person's cardiovascular risk: below 116 mg/dL at low risk, below 100 at moderate risk, below 70 at high risk and below 55 at very high risk, the category that includes anyone who has already had a cardiovascular event. The 2025 update kept those targets and added a new recommendation: measure lipoprotein(a) at least once in a lifetime, because it is a largely genetic risk factor that does not shift with diet and until now went unnoticed.

What cardiovascular risk is and how it is calculated

Cardiovascular risk is an estimate of the probability of a serious event over the coming years, worked out by combining age, sex, smoking, blood pressure, cholesterol and the presence of diabetes or kidney disease. It is done with validated tables and takes two minutes in consultation. The result is what decides whether an LDL of 140 is watched or treated. That assessment is made in the cardiology clinic in Palamós, where the study can also be completed with an ECG, an echocardiogram or a Holter monitor if the history justifies it. Diabetes deserves a separate mention: it raises risk enough to change the LDL target on its own.

What raises cholesterol besides diet

Thyroid, kidney and medicines: the high cholesterol with another cause

Before assuming that a high cholesterol comes from «eating badly», what the MSD Manuals call secondary dyslipidaemia has to be ruled out. Hypothyroidism is the most frequent cause and often goes unnoticed: it raises LDL appreciably and is corrected by treating the thyroid, not with statins. Chronic kidney disease, nephrotic syndrome, hepatic cholestasis, alcohol and certain medicines belong on the same list. It is precisely why a lipid profile is never ordered on its own.

Familial hypercholesterolaemia: the high cholesterol you inherit

Some people are born with a high LDL and can do nothing about it from the kitchen. Familial hypercholesterolaemia affects roughly one in three hundred people according to a review of more than eleven million cases published in 2020, and the vast majority are undiagnosed. The signs that raise suspicion are a persistently very high LDL (above 190 mg/dL in adults), a family history of heart attack or angina before 55 in men and 60 in women, or fatty deposits on the tendons. Picking it up has an important practical consequence: it means siblings, parents and children need testing too, because every first-degree relative has a 50 per cent chance of carrying it.

High triglycerides: a different problem

Triglycerides behave differently. They are considered normal below 150 mg/dL and rise very quickly with alcohol, sugar, the fructose in soft drinks and refined carbohydrates, and also with abdominal weight and poorly controlled diabetes. The good news is that they fall just as fast: dropping alcohol and liquid sugar for a few weeks can change the figure dramatically, which is not the case with LDL.

Above 500 mg/dL the conversation changes. Those figures are no longer only a matter of cardiovascular risk but of acute pancreatitis risk, and they are treated with different urgency and a different approach. If your report carries a triglyceride level in the high hundreds, do not wait for next year's check-up.

What actually changes in the diet

Saturated fat and dietary cholesterol are not the same thing

For decades the cholesterol in food was the villain, and it turns out to be the least important part of the equation. The liver makes most of the cholesterol circulating in you and adjusts production according to what arrives. What does raise LDL consistently is saturated fat: cured meats, processed meat, hard cheeses, butter, pastries and anything containing palm or coconut oil. And above all, the trans fats in ultra-processed products.

Fibre, nuts and olive oil

What works in the other direction is less dramatic and more consistent. The soluble fibre in pulses, oats, barley and fruit traps part of the cholesterol in the gut and stops it being reabsorbed. Unsalted nuts, in a small daily portion, improve the lipid profile across repeated studies. And virgin olive oil as the main fat replaces saturated fat without adding more. Taken together, a well-made and sustained dietary change moves LDL by 5 to 15 per cent: enough to resolve a slightly high cholesterol, not enough when the starting figure is very high. That eating pattern is the one described in our article on the Mediterranean diet, and it has the advantage of already being on our doorstep here.

Exercise, weight, tobacco and alcohol

Regular aerobic exercise has a modest effect on LDL but a clear one on triglycerides and HDL, and above all on overall cardiovascular risk, which is what really matters. The sensible reference is around 150 minutes a week of moderate activity, which on the Costa Brava is covered by walking briskly and without inventing hills.

Losing 5 to 10 per cent of body weight in people who are overweight improves every parameter at once. Stopping smoking does not lower LDL, but it raises HDL and cuts cardiovascular risk more than any other single measure. And alcohol, which enjoyed good press for years on account of HDL, is now regarded as something to limit: it pushes triglycerides up, adds empty calories, and the supposed cardiovascular benefit has not survived more recent research.

When high cholesterol needs tablets

The decision does not rest on a single figure but on the whole picture: calculated cardiovascular risk, the distance between your LDL and your target, age, family history and what lifestyle changes have already achieved. In primary prevention, with low risk and a slightly high LDL, the usual course is three to six months of diet and exercise followed by a repeat test. In someone who has already had a heart attack, by contrast, treatment starts the same day and nothing is waited for.

Muscle pain on statins: what the SAMSON trial showed

This is the most widespread fear and it deserves an honest answer. In a trial published in 2020, sixty people who had abandoned their statin because of side effects were put through a year in which months on the drug, months on placebo and months with no tablet at all were alternated. Mean symptom intensity was 8 points in the months with nothing, 15.4 on placebo and 16.3 on the statin. Put another way: almost all the discomfort appeared with the empty tablet too. That does not mean the pain was invented, because it was real and measured, but that much of it is set off by the act of taking a tablet and the attention we pay to it. Six months after seeing their own results, half the participants were back on a statin. It is a small sample and it does not close the debate, but it changes the conversation: if you stopped yours because of aches, it is worth reopening the question in consultation rather than treating it as settled.

When to book an appointment

It is worth booking if you have not had a blood test in more than five years, if the last one came back with high cholesterol and nobody explained it to you, if you have a family history of heart attack or stroke before 55 or 60, if you have diabetes or high blood pressure or you smoke, or if you have a high figure and want to know what it means in your particular case before changing anything. A well-ordered blood test and half an hour of consultation usually save years of doubt and contradictory advice found online. If you would like to go over the basics yourself, the MedlinePlus page on cholesterol is written in plain language and sells nothing.

Frequently asked questions